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Electrical Engineering
Electrical engineering is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism.
23,056 Questions
What is difference between isolation transformer and earth protection relay?
An isolation transformer is a mutual transformer having a voltage ratio of 1:1, so that the secondary circuit is electrically isolated from the primary circuit, yet subject to the same voltage.
An earth protection relay is a category of protective relay that responds to an earth fault monitored by a current transformer (CT). In the event of an earth fault being detected by the CT, the relay with activate the trip circuit to a circuit breaker which will then disconnect the fault.
What do you mean by electrical engineer practitioner?
One who practises the profession of electrical engineering. An electrical engineer.
What is the purpose of the holding circuit in a magnetic motor starter?
It hold the main contacts closed until the control circuit through the interlock is broken.
What advantage does the current definiton of the meter have over the 1793 statement?
- I have no idea! Answer it yourself you bafoon!
- Go to google
- Type your question
- be all girly happy
How can you rotate the motor in anti clockwise direction?
Assuming (probably incorrectly) that you are talking about car engines:
It probably depends on the engine, and I question why you would ever want to rotate an engine in the opposite direction from how it is designed to run. But if I wanted to move an engine in the wrong direction, I would put a socket wrench on the front of the crankshaft, generally in the middle of the engine's lower pulley. I would first disconnect the negative battery cable, as you never want to risk the engine starting to fire and move on its own when you are working on it.
These generic hints would work on most traditional front engine rear wheel drive american car engines of the 50's thru 70's and beyond. (also on some Volvos, Suzuki Samurais, MBZ, and BMWs I have worked on.)
What is zero voltage regulation in transformers and what it means?
'Zero voltage regulation' indicates that there is no difference between its 'no-load voltage' and its 'full-load voltage' -this is only the case for an 'ideal' transformer.
Why tapping is necessary in a transformer?
Taps are connections to the (usually) high-voltage winding of a transformer which enables minor changes to the turns-ratio to be made in order to make minor changes to the secondary voltage to compensate, where necessary, to a fall in terminal voltage below the regulatory allowance.
There are two types of tap-changing mechanism, 'off-load' and 'on-load'.
Off-load tap-changing mechanisms require the transformer to be isolated before its tap settings can be adjusted, and is normally the case with smaller distribution transformers.
On-load tap-changing can be performed with the transformer supplying its load, usually automatically, in response to changes in its secondary voltage. On-load tap changing mechanisms have a 'make before break' switching arrangement, to ensure that the transformer windings are not open circuited during the operation of tap changing.
What is shunt current and a armature current?
The terms 'shunt' and 'armature' apply to a particular type of d.c. motor, in which the field windings are connected in parallel with the armature windings. 'Shunt' is an archaic term for 'parallel', so the term 'shunt', in this context, means that the field winding is connected in parallel with the armature winding. The terms 'shunt current' and 'armature current', then describe the currents flowing in the shunt winding and armature winding, respectively.
What is the dielectric constant for servo prime 46 lube oil?
ISO-VG 46 oil is a synthetic polyalkenglycol (PAG) oil, therefore the dielectric constant is 6.6-7.3. Please confirm the oil type of Servo Prime 46 lube oil see the chart in the related links section.
Servo Prime 46 is an ISO-vg46 oil made by Indian Oil Corporation Limited (IOCL).
It is also available from these manufacturers:
BPCL (hydrol 46)
Castrol (Hyspin AWS 46)
ExxonMobil Co. India Pvt. Ltd. (MObil DTE Medium)
Shell (Shell Turbo Oil T46)
What is the maximum current of the pole changing motor when running at low speed and high speed?
The maximum current of the pole changing motor when running at low speed and high speed depends on a few different things. The average when begin at low speed and using high speed is 1800 RPM points.
A short circuit between adjacent turns of the same winding will cause the turns ratio of the transformer to change. A short circuit of this nature may not cause the transformer to become disconnected, so the situation could last for a long time.
In larger utility transformers, the gases formed by the arcing between turns will collect in the Buchholz relay, situated between the transformer and its expansion tank, which will then initiate an alarm inside the substation.
Why power factor can not be unity?
Power factor can be unity. If the load is purely resistive, then the load current and supply voltage are in phase, and the load will have unity power factor.
How can you get 3 phase supply from single phase supply by using only transformers?
You cannot. By definition, the potential of each line must be displaced from each other by 120 electrical degrees, and this is only achievable from a three-phase source.
How do you calculate the over load and short circuits to use fuses?
By referring to the manufacturer's characteristic curves for the fuse. There are different curves for different types of fuse (e.g. rewirable, cartridge, etc.). Essentially, these curve will tell you how quickly the fuse will operate for any value of overload current.
How do find voltage from mvar and mw?
mw is the unit of real power and mvar is unit of reactive power. You should now the current and power factor angle to calculate the voltage.
p=vi cos pi
q=vi sin pi
AnswerI think you mean MW, not mw -capital 'M' mega; lower-case 'm' milli!!! And the symbol for watt is a capital 'W', not a lower case 'w'. Also, I think you mean 'Mvar'(mega, not milli!).
What are the factors affecting the stability of a Q-point?
(1) current amplification factor due to change in temperature.
(2) collector current because of variation in leakage current.
Why is a capacitor connected in series with starter winding?
In single phase motors, there are two windings.
1)Main winding
2) starter (auxiliary) winding.
As per the double revolving theory in 1 phase machines, motor can rotate if current in the starter winding have near to 90 deg. phase shift wrt main winding.
Now current flowing through capacitor leads by 90 deg. Ideally. So this is how we can get two currents which are having phase shift wrt each other. And the machine can rotate.
Is an AC generator can use AC motor and vice verso?
Are you planning to build a perpetual motion machine in which the power generated by an AC generator is used to run an AC motor which is used to run the same AC generator which provides it with power? Because that won't work. Yes, you can use a motor to generate electricity, and you can use electricity to run a motor, but the process is not 100% efficient and if you try to make it a closed loop, it will run down fairly quickly. So, what do we actually do? We use fuel to run an AC generator, or we use waterfalls or wind, or some other energy source, and then we use the power to run our motor.
How long does it take 10C to flow past a point if the current is 5A?
curent= couloumb/ time
5=10c/t
t =10c/5a
t =2sec
